Humidifying of air



Dec. 24, 1940. 3 GRUBB 2,225,954

HUMIDIFYING OF AIR Filed Dec. 1, 1937 2 Sheets-Sheet 2 BY Maj-1:232 M [1M )ZTORNEY.

Patented Dec. 24, 1940 UNITED STATES PATENT g OFFICE HULIIDIFYING OF AIR Application December 1, 1937, Serial No. 177,450 In Germany December 9, 1936 7 Claims. (01. 237-78) My invention relates to humidifylng of air, and it is an object of the invention to provide an improved method and apparatus for humidifying air in enclosures, such as rooms, offices, and the like.

The above and other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings forming a part of this 10 specification, and of which:

Fig. 1 is a vertical sectional view of humiditying apparatus embodying the invention;

Fig. 2 is a front view, partly in section, taken on line 2-2 of Fig. 1;

Fig. 3 is a front view of humidifying apparatus illustrating a modification of the invention;

Fig. 4 is an end view of the humidifying apparatus shown in Fig. 3;

Fig. 5 is an enlarged sectional view taken on 30 line 5-5 of Fig. 3 to illustrate parts of the humidifying apparatus more clearly;

Fig. 6 diagrammatically illustrates a system which may be employed to circulate water in the humidifying apparatus shown in the preceding Fig. 7 illustrates a further modification of the invention; and

Fig. 8 is a fragmentary sectional view taken on line 88 of Fig. 7 to illustrate parts of the hu- 30 midifying apparatus more clearly.

Referring to Fig. 1, a heating element or radiator. I2 of a heating system, such as a steam or hot water heating system, is located in a window niche II). In order to simplify the drawings the 5 admission and discharge conduits for the heating agent, such as steam or hot water, have not been shown. The heating element I2 is concealed within a housing including a vertical closure plate II which is provided with a plurality 40 of openings 9. An evaporator plate I3 is arranged. at one side of radiator I2 and slopes away from the radiator, as clearly shown in Fig. l.

The upper part of plate l3 rests against the surfaces of the radiator. In order to further increase the heat transmission from the radiator I2 to the plate I3, the rear side of plate I3 may be provided with cross ribs (not shown) which extend between the individual sections of the radiator and bear against the broad side of these 50 sections. The plate I3 is bent back upon itself to form a'tube or channel M which extends in the longitudinal direction of the radiator. The upper part of plate I3 is bent back upon itself in such a manner to provide a slot or elongated 55 space to receive the upper end of a strip of maplate I3 extends.

terial I6. The ends of channel I4 are provided with end plates which only need be water tight at their lower portions.

The plate I3 is provided with vertical depressions or notches 8, as shown most clearly in Fig. 5 2. The strip of material I6 serves as a sealing ledge and on the side thereof which bears against the front side of the evaporator plate I3 the strip is provided with vertically extending depressions or slits. The strip l6 may be formed of 10 rubber, such as semi-vulcanized rubber, or of any other suitable material. The depressions in the strip I6 provides narrow channels in which water is directed in a downward direction. The depressions or notches 8 in plate I3 extend upward to the strip I6 and serve to distribute the water which trickles downward over substantially the entire area of plate I 3.

Below the radiator I2 is arranged an open accumulation vessel into the bottom of which the go The accumulation vessel 20 is of substantially the same width and length as the radiator I2. The accumulation vessel 20 is preferably heat insulated and of suflicient size to hold a relatively large volume of water. Below the accumulation vessel 20 is provided a second closed vessel 2| which is preferably sound insulated and covered with a layer 22 of suitable heat insulating material. A conduit I5 extends upward from the bottom of vessel 2| and is connected at its upper end to a horizontal pipe or manifold I8 which is arranged within tube I4 and provided with a plurality of aligned openings II in the lower portion thereof. The conduit I5 and manifold l8 are preferably of such diameter 5 that vapor and liquid can freely pass each other.

From the lower part of accumulation vessel 20 a conduit 23 extends downward and is connected at its lower end to a check valve 24 located in the lower part of vessel 2|. The check valve 24 permits downward flow of liquid in conduit 23 and prevents liquid from flowing from vessel 2| into accumulation vessel 20. The, check valve 24 may contain a valve member which is lighter than water and tends to close against its seat due to buoyancy.

The vessel 2| is divided into two parts or compartments 21 and 28 by a partition or wall 25, whereby the two compartments are in communication with each other through the space above the partition. The right hand compartment 21 of vessel 2| is provided with an electrical heating element 26 which is preferably removably secured in position.

Assuming that accumulation vessel 2!) filled with water, which may be indicated by a suitable water level indicator, the pressure of the water column in accumulation vessel 20 and conduit 23 is sufficient to cause check valve 24 to open. This permits water to flow into vessel 2| in connection with which some air escapes through conduit I5 and tube I4. By connecting the heating element 26 to a source of electrical supply, water is heated and evaporatedin compartment 21. The heating element 26 is preferably located at such a height in vessel 2| that the greater part thereof is surrounded by water. The water vapor formed due to heating mixes with any air present in vessel 2| whereby a pressure is produced to cause water from the unheated compartment 28 to rise in conduit I5 and into manifold I8.

The water flows through the'openings or perforations H in manifold I8 and into the tube or channel I4 and collects in the lower part of the latter.' The water stored in tube I4 passes through the openings formed between the strip I6 and plate I3 and trickles downward along the slightly inclined plate I3, whereby the latter becomes completely wetted. Due to the vapor pressure in vessel 2| the water will flow upward through conduit I5 until the water level in vessel 2| has dropped below the lower end of the conduit, whereupon water vapor then flows through the conduit to relieve the vapor pressure in vessel 2|.

When the vapor pressure in vessel 2| is relieved the check valve 24 again opens whereby cool water fiows from the accumulation vessel 20 into the vessel 2|. The left-hand compartment of vessel 2| is filled first and water then flows over the partition 25, whereupon the righthand compartment 21 is then filled. With this arrangement water previously heated by heating element 26 is retained in the right-hand compartment 21.

In general, it isadvisable to make the capacity of compartment 21 as small as possible, so that the amount of liquid therein is just sufficient to eflect lifting of water from the left-hand compartment 28. If the amount of water evaporated in compartment 21 is such that heating element is surrounded only by water vapor, water vapor will be generated suddenly when the compartment is again filled with water. The sudden generation of steam in this manner will be the more active the greater the heat storing ability of the heating element 26.

In the embodiment of Figs. 1 and 2 the humidity apparatus has been illustrated in connection with a radiator or heating element of a type now generally used. In Figs. 3 to 5 inclusive I have shown a heating element or radiator of different form which is particularly arranged for humidifying of air in accordance with my invention. The different parts which are similar to those illustrated in Figs. 1 and 2 are designated by the same reference numerals.

In Figs. 3 to 5 inclusive the radiator 30 is made of steel or iron sheeting, such as stainless or roughly chrome-plated steel, for example, which is bent to form a radiator of the shape shown in Fig. 4. One edge of the metal sheet forming the radiator is bent to provide the tube or channel I4, and the other edge 32 is secured, as by welding, to the opposite side of the radiator. The manifold or pipe I8 is arranged within channel I4 and is secured in any suitable manner to the top wall portion thereof. The strip I6 extends into a slot or elongated space formed in the lower part of channel I4 and bears against a side wall of the radiator 30. The radiator 30 is provided with end cover plates 33 and connected in the usual manner (not shown) to the pipes of a steam or hot water heating system.

The accumulation vessel 20 is filled with water which, as explained above, is raised from vessel 2| through conduit I5 and into manifold I8. The water flowing and trickling downward over the surface of radiator 30 is readily evaporated to increase the humidity of air fiowing in contact therewith. Not only is the humidity of air effectively increased but transmission of heat to the ambient air is also realized which is about five to six times greater than that in radiators of the type which are only contacted by dry air. Thus, in spite of the substantially even but preferably roughened surfaces of radiator 30, the size of the radiator may be reduced considerably as compared with radiators which only contact dry air, due to the increase of heat transmission to the ambient air.

The evaporation of water may be effected in accordance with my invention with any type of heat source which is maintained above room temperature. Since it is always possible to keep the evaporating surface moist and the surface uniformly heated, a relatively large evaporation surface is provided. When the transmission of heat from the radiator to the evaporating surface is efi'ected completely or partially by radiation, it is desirable to make the radiating and also the absorbing surfaces black. The evaporating surface is preferably disposed at a region where the natural draft or flow of air is relatively high. In Fig. l, for example, air enters the space I I through the lower openings 9 and fiows upwardly in a direction counter-current to the downwardly flowing water. The humidified air then is discharged through the upper openings 9.

The evaporating surface is preferably arranged at a small angle with respect to the vertical plane to insure uniform distribution of water flowing over the evaporating surface. If desired, the evaporating surface may be provided with narrow grooves extending in a horizontal or vertical direction, or the surface may be roughened, as by sand blasting or by electrochemical treatment. When the evaporating surface is provided with narrow grooves or roughened, the distribution of liquid is aided by capillary action. The distribution of liquid may also be effected by imparting to the surface of the evaporation member the properties of a porous body. In such case it is desirable to use a relatively hard material for the evaporating surface, such as glass, for example, whereby the evaporating surface may be washed and cleaned as frequently as desired without changing the capillary properties of the surface.

By providing an evaporation surface which is always moist, a further advantage results in that it acts as an air cleaner by, removing dust from the air. The dust in the air collects on the surface of the evaporation member and accumulates in the vessel 20. A dust trap, such as .a filtering screen, for example, may be provided in vessel 20 to trap the dust and prevent the latter from entering conduit 23.

The evaporation surface may also be utilized to effect evaporation of inhalation agents, perfumes to improve the air, or disinfecting agents. Any disinfectants employed must be non-toxic and chemically inert with respect to the surfaces which come in contact with the water. As suit able disinfectants, boric acid, A or B-naphthol, or chloramine may be employed.

After the heated evaporating surface is once wetted it can be easily maintained in this condition. When the heated evaporating surface is substantially dry, as when starting the humidifying apparatus after a shut-off period, it is imperative to obtain complete wetting of the surface in a dependable manner. For this reason the distributing strip I6 is provided with slit surfaces. When the grooves or flutings are greater than 0.5 mm. in width, it is desirable to roughen the slit surfaces. When the grooves are once filled with water, the water is distributed very rapidly over the evaporating surface. The provision of slight projections on the evaporating surface which extend in a horizontal direction at a relatively great distance from each other effect an accelerating action.

When the quantity of water raised into manifold |8 is not very great, a uniform distribution of Water may not be effected along the entire length of channel M. A uniform distribution of water over the evaporating surface is effected even under these conditions by the provision of the strip Hi. This may be accomplished by arranging the strip |6 so that its lower edge bears directly against the evaporating surface while its upper edge is spaced from to 3 mm. from the evaporating surface. With the strip l6 and evaporating surface forming a sharp acute angle, a narrow space is provided in which the quantity of water tends to equalize and distribute itself along the length of the strip I6, due to capillary forces which also act in a horizontal direction on the water,

If desired, the water from conduit |5 may be admitted at one end of strip I6. To effect the desired distribution of water in such case, a strip of material formed of rubber or metal may be inserted in the longitudinal direction of strip l6 between the latter and the heated evaporating surface, such additional strip being slightly inclined to the horizontal plane. By providing such an additional strip, which may replace the channel l4, water admitted to one end of strip i6 is guided along the'additional strip by capillary forces and by gravity. In this manner the water is guided obliquely downward and distributed in the vertical grooves of the strip IS.

The grooves in strip l6 need not necessarily extend in a vertical direction. It is only necessary to provide such depressions or channel-like indentations in strip Hi to produce capillary passage openings at the lower edge of the strip. By roughening the surface sufliciently, these requirements are fulfilled. When the heated evaporating surface i3 is made of metal, the spreading of water on the surface can be facilitated by added traces of soap or alkali.

The distribution of water is improved greatly when relatively large quantities are raised into channel i4 per unit of time. It is desirable, therefore, to provide a liquid circulation system in which comparatively large quantities of water are admitted into channel l4 during each pumping period. The intervals of time between the pumping periods may deviate, depending upon the condition of the heated evaporating surface and the distributing device l4 and I6. The property of the heated evaporating surface to store water is a factor to be considered in determining the intervals of time between the pumping periods.

The humidifying systems described above may be supplied with water in any suitable manner. Water may be supplied from the radiator l2 through a suitable liquid level control. In such case, it is desirable to provide a radiator in which the inner surfaces as well as the connecting conduits are not likely to corrode. Independent water conduit, connections may be provided for each accumulation vessel 20.

Although an electrically operated mechanical pump may be employed to raise water intermittently from vessel 2|], 9. heat operated silent pump having no moving parts is particularly advantageous.

Since a relatively small amount of.

water vapor or steam is required to raise water by pressure, the quantity of energy required to produce steam is relatively small.

-In order to reduce the condensation of water vapor which occurs on the surface of water in compartment 28, a float may be provided in this compartment. Such float may be formed of a suitable heat insulating material, such as cork or the like, and provided with a protective layer of a substance especially resistant to water.

Instead of a check valve 24, a suitable float valve may be employed to control flow of water from accumulation vessel 20 into vessel 2|. Fig. 6 I have shown a modified system in which the necessity of providing a check valve or float valve is avoided. In this arrangement the conduit connecting the accumulation vessel 20 and vessel 2| is of inverted U shape. The highest point of conduit 23 is located at a higher level than the manifold I8 and the downward directed arm 5| extends into a compartment 52 of the accumulation vessel 2|! formed by a partition 51. The lower part of partition 51 is provided with a small opening 53, whereby compartment 52 is in liquid communication with the remaining part of the vessel 20. The vessel 2| is connected by conduits 58 and 59 to a chamber 54 within which the electrical heating element 26 is positioned. The lower end of conduit I5 is provided with a Ubend 55 which extends below the vessel 2|.

When the liquid in vessel 2| is subjected to the pressure of vapor produced in chamber 54, the water in vessel 2| is forced upward in'conduit l5 into manifold l8, as explained above. Due to thevapor pressure in vessel 2| water is also forced upward in conduit 23. The liquid columns in conduits l5 and 23' are practically the same and differ only by the immersion depth of arm 5| into the liquid in vessel 20. With liquid in the left-hand arm of conduit 23, the air in this conduit is pressed into the arm 5|.

Since conduit 23 is connected to vessel 2| at a higher level than conduit 55, vapor will first the liquid in conduit 23 is raised and flows into the arm 5|. The liquid in arm 5| expels the column of air through the lower discharge end and, when all of the air is expelled, the conduit 23 only contains vapor and liquid.

When the above takes place, the column of liquid in conduit l5 drops and flows back into vessel 2|. The water returning to vessel 2| is comparatively cool and causes some condensation of vapor in vessel 2|, thereby causing the pressure in this vessel to drop. This also results in a drop in pressure in conduit 23, whereupon water is drawn up out of compartment 52 of vessel 20.

The vapor in conduit 23 is also cooled, as by the cooling fins 56 on arm 5|, thereby causing condensation of vapor in conduit 23 to effect a further drop in pressure. With such drop in pressure, the liquid column in arm 5| gradually reaches the overflow point 50 and then flows downward into vessel 2|. The parts of the liquid circulation system just described are so dimensioned that the siphoning of liquid takes place at a greater rate than the rate at which liquid flows through opening 53 into compartment 52 from the remaining part of vessel 20. The parts are so arranged that compartment 52 is emptied substantially at the time when vessel 2| is filled with water to the desired level. When the liquid level in compartment 52 falls below the lower end of arm 5|, air is drawn into arm 5| to break the siphon.

The flow of water over a heated evaporating surface can also be effected by siphon action, as shown in Figs. 7 and 8. In Fig. 7 a Dewar vessel 66 is provided with an air-tight filling cap 6| and connected by an air conduit 62 and a liquid conduit 63 to a pressure vessel 64. From the pressure vessel 64 an evacuating pipe 65 extends upward and is provided at its upper end with a cup-like enlargement 66 which is open to the atmosphere. From the lower part of pressure vessel 64 conduit l5 extends upward and is connected to channel I4 which, as shown most clearly-in Fig. 8, is provided with an upper indented portion. The lowermost part of the depression or indentation is provided with a slit 61.

From the channel l4 a plate ,68 which is preferably dark extends downward into an open collection basin 69. The basin 69 is provided with a drain valve 10 for removing water from the basin. The entire apparatus is supported or mounted on legs or feet I l. I Y

From the channel I4 a broad fabric wick 12 formed of linen or cotton, for example, extends downward into collection vessel 69. A fabric roll 13 which is filled with a suitable substance, such as sand, for example, is positioned in the upper part of the depression to press the upper portion of wick l2 firmly against the slot 61 in channel I4.

When operation of the apparatus is started, the cap 6| is removed and the system is filled with water until the liquid level reaches the cup 66. The cap 6| is then screwed in position in the Dewar vessel 60. The conduits 65, 62, 63, and I5 and the pressure vessel 64 are now completely filled with water and, since the liquid level in cup 66 and Dewar vessel 60 is higher and above the slit 6! in channel H, a certain quantity of liquid fiows to the wick l2 through conduit I5 and channel |4 due to siphon action. In this manner the wick 12 is wetted when operation of the apparatus is started.

Due to wetting of the wick 12 by liquid which has siphoned through conduit |5 when the system is filled with water, the siphoning action tends to continue in the direction of the collecting vessel 69. from conducting water too quickly so that it collects unnecessarily in the collection vessel 69,

q the pressure vessel 64.is connected to the Dewar vessel 66. The apparatus is so arranged that,

\ after complete wetting of the wick, the conduits 66 and 62 are drained of liquid, whereby the action of the Dewar vessel enters into operation and the liquid level in the pressure vessel 64 is maintained at the height indicated at H in Fig. 7.

After the above occurs, the force effective for siphoning water is equal to the height a which can be determined by adjusting the lower end of In order to prevent this siphoning action conduit 62 in pressure vessel 64. This may be accomplished by providing a hollow threaded sleeve member 14 to permit vertical adjustment of conduit 62 in pressure vessel 64 through a packing or stufiing 15. By selecting a fabric for wick 12 of suitable porosity, it is possible to ad- .just the flow of water through conduit l5 into channel |4 so that the wick is maintained in a wetted condition without any pronounced dripping of water at the lower edge of the wick.

The use of a fabric as wick |2 is particularly desirable since such material can be exchanged and readily cleaned. In place of fabrics, however, other porous substances may be readily used. Further, the valve closure 13 which cooperates with the slit 6! may be replaced with any desired porous substance which permits liquid to pass through the slit but which prevents the passage of air.

When a wick 12 of predetermined porosity is employed, the Dewar vessel 60 may be eliminated if the space conditions otherwise are favorable. If the pressure vessel 64 is made cms. long and 20 cms. wide, the height of the liquid level in the pressure vessel will only drop 3 cms. with evaporation of 10 liters of water. When selecting a wick 12 of suitable porosity, such fluctuation of liquid level is practically unimportant.

A combination of a heat pump and a siphon may be used to cause flow of water over the heated evaporating surface. In such case the heat pump may be primarily employed to raise a part of the reaction column in conduit l5 of the siphon to reduce the likelihood of air entering through the valve closure formed by the fabric roll 13 and slit 61, The part of the reaction column I5 of the siphon not raised by the heat pump serves to reduce the rate of flow of the water from the heated evaporating surface. If desired, the part of the reaction column worked by the pump may be controlled thermostatically.

Such a combination of a heat pump and siphon possesses the advantage that the evaporation surface may be made relatively high. If desired, the pumping mechanism of Fig. 2 may be associated with the vessels 64 or 60 instead of acting on the channel I 4.

The danger of liquid flowing too rapidly over the evaporation surface may be compensated not only by a heat pump, by a siphon effect, or by a combination of both, but also by a simple float valve. If the channel I4 is made relatively large so that it can receive the entire quantity of water to be evaporated and an excessive quantity flows therefrom into the collecting basin 69, it is possible to control the rate of flow of water from channel M by a suitable valve therein which is connected to and responsive to a float valve in the collecting basin.

While I have shown and described particular embodiments of the invention, I do not wish to be limited to the particular arrangements set forth, and I therefore aim in the following claims to cover all modifications and changes that fall within the true spirit and scope of the invention.

What is claimed is:

1. Apparatus for heating and humidifying air comprising the combination of a heating system providing a first circuit for a heating fiuid and including a radiator in an enclosure having a vertically extending heating surface adapted to be heated by the heating fluid circulating in said first circuit, a second circuit in which Water out of contact with said heating fluid is continuously circulated, said second circuit being formed and arranged with respect to said vertically extending heating surface so that water in its path of flow in said second circuit flows in contact with and over said vertically extending heating surface, said heating fluid in said first circuit being effective to heat said water flowing over said heating surface to cause at least partial evaporation thereof into air flowing past said heating surface to increase the humidity of the air while simultaneously heating the same, and said radiator having heat transfer surface portions which are normally in a dry state whereby heat is also transferred directly to air flowing over such surface portions in addition to the heat transferred to air by said vertically extendingheating surface.

2. Apparatus as set forth in claim 1 including an accumulator for collecting unevaporated water flowing from said vertically xtending heating surface, and structure to raise water from said accumulator to a higher level for flow again over said heating surface, said structure including means to vaporize water to form vapor and alternately trap such vapor above a surface level of water and subsequently remove the vapor to exert a pulsating lifting force.

3. Apparatus as set forth in claim 1 including an accumulator for collecting unevaporated water flowing from said vertically extending heating surface, and structure to raise water from said accumulator to a higher level for flow again over said heating surface, said structure including means to vaporize water to form vapor and alternately trap such vapor above a surface level of water and subsequently discharge the vapor to the atmosphere at the higher level to exert a pulsating lifting force.

4. Apparatus as set forth in claim 1 including an accumulator for collecting unevaporated water flowing from said vertically extending heating surface, and structure to raise water from said accumulator to a higher level for flow again over said heating surface, said structure including means to vaporize water to form vapor and alternately trap such vapor above a surface level of water and subsequently remove the vapor by condensation to exert a'pulsating lifting force.

5. Apparatus as set forth in claim 1 comprising structure including siphoning means to raise unevaporated water flowing from said heating surface to a higher level for flow again over said vertically extending heating surface.

6. Apparatus as set forth in claim 1 including an accumulator for collecting unevaporated water flowing from said vertically extending heating surface, and structure to raise water from said accumulator to a higher level for flow again over said heating surface, said structure including an electrical heating element arranged to vaporize water in said accumulator to form vapor and alternately trap such vapor above a surface level of water and subsequently remove the vapor to exert a pulsating lifting force.

7. Apparatus as set forth in claim- 1 including means to cause water to flow over substantially the entire area of said vertically extending heating surface, and said surface being porous to facilitate distribution of water flowing thereover.

GUNNAR GRU'BB. 

